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What happens to HDD spaces created by deletes?


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#1 zzzz

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Posted 01 September 2016 - 04:37 PM

I am digitising many VHS tape videos to store on an external 3 TB HDD.

 

Now in the initial pass I have the unedited video on that HDD. Then I edit out bits and pieces and save that to the same HDD and delete the unedited version.

 

Now, am I making gaps and wasting that space on the HDD where the deleted videos were or what? 

 

I have read that defragging in this situation does not regain much if any space and is not worth doing -

 

Can anyone clarify this point please.

 

 



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#2 JohnC_21

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Posted 01 September 2016 - 04:55 PM

When you delete a file in Windows the sectors used by the file, which can be anywhere on the disk, is marked as deleted but in effect the file data is still there. That is why you can use a utility to recover the file once it is deleted if those sectors are not written to. Because the sectors are marked as deleted if you save some other file to disk that file may overwrite those sectors mark deleted. You do not lose disk space. Even if you have gaps Windows will use those gaps when saving files. If you have Windows 7 or later the disk is automatically defragged every Wednesday.

 

The post by Solandri here has a good explanation.



#3 zzzz

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Posted 01 September 2016 - 05:43 PM

I replied to your post, for which thanks, but clicking Post resulted in this website becoming offline and just now getting it back!
 
So,I should have mentioned I'm using Win10.
 
What would happen if the deleted 'spaces' were always smaller than larger saved files so those couldn't 'fit' into that deleted space if that was the only operation?  (Altho I was initially thinking about the slightly smaller files replacing unedited files so leaving very small gaps and what happens to them)
 
Would defragging solve both scenario?
 
Perhaps I should have said in my initial post that my edited file cannot overwrite the unedited file space as it is still there before deleting. So perhaps the second edited file, if not larger, overwrites the space where the first unedited file was deleted. Yes? Leaving a gap and in my case a pretty small one.

Edited by hamluis, 02 September 2016 - 01:05 PM.


#4 JohnC_21

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Posted 01 September 2016 - 06:01 PM

A hard drive is divided in sectors and they are all the same size, usually 512 bytes . NTFS, the file system you would be using on Windows has a cluster size of 4kb, made up of sectors but it does change depending on the size of the drive. So, a small file of 800 bytes would still use 4kb of space. A large file uses more sectors than a small file. Once the large file is deleted Windows could assign more than one file to those sectors occupied by the large file.

 

http://www.file-recovery.com/recovery-hard-disk-drive-sectors.htm

 

https://support.microsoft.com/en-us/kb/140365

 

Perhaps I should have said in my initial post that my edited file cannot overwrite the unedited file space as it is still there before deleting. So perhaps the second edited file, if not larger, overwrites the space where the first unedited file was deleted. Yes? Leaving a gap and in my case a pretty small one.

If you edit a file and you save it as a different name then you would be using more space. If the edited file is save with the same name then it overwrites the file and if larger would use more sectors and those sectors would be at a different location on the drive. If the second edited file is not larger then is it possible it would use the space of the previous file. It all depends on where Windows decides to place the file. 



#5 zzzz

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Posted 02 September 2016 - 06:43 AM

Thank you very much for that - I have a much better understanding of the issue now. 

 

Quote: "If you edit a file and you save it as a different name then you would be using more space."

 

In my case what happens is the unedited file is auto saved to the HDD and has a 'name' of numbers. When edited it is saved to that HDD with a 'name' of different numbers (date etc.) Then I change that 'name' to a real description. Well Windows is doing its job so I'm thankful for that.






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